Clinical utility of electrophysiological evaluation in Crigler-Najjar syndrome.

We evaluated the neurological and neurophysiological features in ten patients with genetically characterized Crigler-Najjar (CN) syndrome: four with typical type I CN had undergone orthotopic liver transplantation (OLT); six had type II CN, and three of them developed severe hyperbilirubinemia with a limited response to phenobarbital leading to an intermediate phenotype I/II. Clinical neurological and multimodal electrophysiological evaluations [electroencephalogram (EEG), visual (VEPs), motor (MEPs) and brainstem auditory (BAEPs) evoked potentials] were performed. Neurological examinations showed mild hand tremor in four patients (one pre-OLT and one post-OLT type I, two type I/II). EEG revealed high voltage paroxysmal discharges in four patients (three type I/II, and one type I with a marked improvement after OLT). VEPs showed P100 wave increased latency in five patients (three type I, and two type I/II considered for OLT evaluation). MEPs showed prolonged central motor conduction time in five patients (two type I; one type I/II; two type II). Only EEG and VEPs findings showed a correlation with high bilirubin levels. BAEPs were normal. In conclusion, VEPs and EEG contribute to identify and monitor bilirubin neurotoxic effects, and may play a decisional role in some cases of severe hyperbilirubinemia without overt neurologic damage.